1. Cross Reference to the Invention
This invention relates to co-pending U.S. patent application Ser. No. 971,499 "Dust Removing Mechanism in Open-End Spinning Frame" filed on Dec. 20, 1978 by Tsutomu Miyazaki et al, now U.S. Pat. No. 4,204,393, and assigned to the same assignee as the present application.
2. Field of the Invention
This invention relates to a dust removing mechanism in an open-end spinning frame and more particularly to improvements in a dust removing mechanism of the type wherein centrifugal force acting on dust entrained in opened fibers causes the dust to be removed from the opened fibers through a dust removing opening provided in a casing for an opening roller while a silver is being opened into the individually opened fibers and delivered by the opening roller.
3. Description of the Prior Art
Where impurities and foreign matter such as dust, neps, leaf pieces, seed pieces and chemical adhering substances (inclusively referred to as "dust" hereinafter) are entrained in material fibers, there is a tendency that the operation for collecting the fibers in a twisting region and spinning them into a twisted yarn becomes unstable, resulting in poor yarn quality. In order to avoid this tendency, various designs of dust removing mechanisms have been proposed, in which a dust removing opening is formed at a part of a fiber opening region, wherein a fiber opening roller is disposed upstream of the twisting region, and dust is caused to fly off through this dust removing opening by the centrifugal force acting thereon. However, satisfactory results could not be obtained by these designs.
Since the ejection of dust through the dust removing opening depends on the centrifugal force acting thereon, the fibers per se also may be ejected along with the dust by the action of the centrifugal force on the fibers. As a means for preventing the ejection of the fibers, a method has been proposed in which an auxiliary air stream is produced to flow into the dust removing opening. Dust of relatively large mass can fly off from the dust separating zone against the opposing force of this auxiliary air stream, but the fibers having a relatively light mass are prevented from flying off from the dust separating zone by the auxiliary air stream entering thereinto and are delivered to the twisting region by the opening roller. In this method, however, the dust-removing effect is remarkably influenced by the intensity of the auxiliary air stream and the direction of flow thereof, and therefore delicate adjustment of the air stream is required at the dust removing opening. Such method is disclosed in U.S. Pat. Nos. 3,986,327 and 4,036,002.
Further, a method has been proposed, in which to promptly remove the dust ejected through the dust removing opening and thereby prevent the dust from remaining in a region adjacent to the dust removing opening, in addition to the auxiliary air stream, a dust discharging air stream is provided so as to flow into a dust discharging zone adjacent to the dust separating zone and to be introduced therefrom into the dust separating zone. In this method, adjustment of the intensity relation between the dust discharge air stream and the auxiliary air stream in the dust separating zone is very complex and difficult. More specifically, in order to promptly discharge the dust ejected through the dust removing opening and separating zone, it is necessary to produce the dust discharging air stream at a position close to the separating zone and also to increase the intensity of such a dust discharging air stream. However, if the intensity of the dust discharging air stream is too strong, the dust discharging air stream will adversely influence the separating zone, thus disturbing the smooth flow of the auxiliary air stream, and also the phenomenon will occur that the fibers are also sucked into and discharged through the dust separating opening. Such an undesirable phenomenon can be avoided by reducing the intensity of the dust discharging air stream, but in that event depositing and adhesion of the dust and fine fibers onto the walls of the separating zone and dust discharging zone will then occur. When the dust adheres to the walls, leaf pieces and the like act as nuclei and fine fibers adhere to and gather around the nuclei. Thus, the dust gradually accumulates on the walls. When the degree of accumulation of dust on the walls exceeds a certain extent, it will be scattered in the form of large masses by the action of the air streams, and these masses will come under the influence of the auxiliary air stream and will be directed toward the dust removing opening. As a result, there will occur the most undesirable phenomenon that these dust masses are blown back into the dust removing opening. This actually occurs when adjustment of the air streams is not carried out appropriately. Such method is disclosed in U.S. Pat. Nos. 3,892,063 and 4,009,562.
It is therefore understood that, in the dust removing method for the open-end spinning frame, in which the auxiliary air stream for catching fibers from the dust removing opening and the dust discharging air stream for discharging the dust are utilized, it is most preferable that the auxiliary air stream be applied in such a way that the ejection of dust from the dust removing opening is allowed, but the ejection of fibers from the dust removing opening is prevented, and that the influence of the dust discharging air stream on the dust separating zone is reduced to a minimum level while at the same time the dust discharging air stream is capable of flowing strongly through the dust discharging zone.
The invention in the afore-mentioned co-pending application is directed toward realizing the said preferable conditions in the dust removing method. More specifically, said co-pending application discloses a dust removing mechanism for an open-end spinning frame, in which a partition plate is disposed in such a manner as to define a dust separating zone communicating with atmospheric air to generate an auxiliary air stream directed to a dust removing opening, and a dust discharge promoting zone having a suction opening and a confronting air intake opening for generating a linear stream of air for dust discharge; a passage communicating the dust separating zone with the dust discharge promoting zone is provided as a transfer passage for the dust ejected from the dust removing opening, downstream of the dust removing opening with respect to the rotation direction of an opening roller; and the wall of the dust separating zone on the downstream side is so inclined that the dust flying off through the dust removing opening bounces back to the communicating passage and is finally introduced into the dust discharging zone. In this dust removing mechanism, the partition plate defining each of the dust separating zone and dust discharge promoting zone regulates the flow pattern of the dust discharging air stream and prevents any serious influence of the dust discharging air stream on the dust removing opening, and dust ejected through the dust removing opening is caused to bounce off the inclined walls due to the kinetic energy of the flying dust and is positively discharged from the suction opening into a dust collecting zone, while being carried by the dust discharging air stream in the dust discharge promoting zone.
Although the dust removing mechanism disclosed in said co-pending application provides a higher rate of dust removal than that attained by any of the dust removing mechanisms shown in U.S. Pat. Nos. 3,986,327, 4,036,002, 3,892,063 and 4,009,562, it still involves the disadvantage that the wedge-shaped partition plate can cause some of the dust bouncing off the partition plate to be moved back into the dust removing opening.
It is therefore a principal object of this invention to provide a dust removing mechanism, which eliminates the disadvantage of the invention in the afore-mentioned co-pending application without detriment to the advantages thereof.